The design of a novel protein whose catalytic activity is controlled by light may or may not have direct nanotech applications, but it represents another milestone in engineering proteins. In this case scientists were able to engineer functional communication between two unrelated proteins by taking advantage of the fact that each protein exhibits allosteric regulation. In allosteric regulation the binding of a small molecule to one surface of a protein regulates the function of distant part of the protein. By combining a light sensing protein and an enzyme at their allosteric surfaces, they were able to functionally connect the two proteins so that light controls the enzymatic activity. From ScienceDaily “Scientists Use Light To Control Proteins“:

A team of researchers from Penn State and the University of Texas Southwestern Medical Center has discovered a way to use light to control certain proteins that catalyze biochemical reactions.

“This is one of the first examples of someone successfully controlling the activity of a protein using light,” said Stephen Benkovic, Penn State Evan Pugh Professor of Chemistry, holder of the Eberly Family Chair in Chemistry, and one of the team’s leaders. “The technology one day could be expanded to have multiple uses, including the ability to turn off the activities of some disease-causing proteins in the cell,” he said.

The team’s results will appear in the 17 October issue of the journal Science [abstract].

In their experiment, the scientists designed a hybrid protein by inserting a light-sensing protein from an oat plant into an enzyme — a type of protein that catalyzes biochemical reactions — from the bacterium E. coli. After engineering the two components together, the researchers found that the enzyme’s activity could be manipulated by shining a light on the light-sensing protein, which the scientists refer to as a “domain.” “The technology works like a light switch,” said Benkovic. “When we shine a light on the light-sensing domain, the enzyme’s activity increases, and when we shut the light off, the enzyme’s activity decreases.”

The researchers conclude their Science paper with the observation:

The engineering of light-dependent allosteric control in the LOV2-DHFR chimera represents an initial step toward a general scheme for the creation of allosteric multidomain systems. As methods become more refined, the computational prediction of potential allosteric surface sites should be combined with physics-based interface design and experimental screening to design high-performance allosteric systems.

A system in which a substantial number of protein domains can be functionally connected to implement multistep reactions might be of use in the development of productive nanosystems.—Jim